Started CP4 bake today, with some hiccups. The heater was being controlled by a TC that was in a blind spot and not reading a well represented temperature, causing the enclosure to heat up too fast. The heater is now controlled via TC#1 which is clamped to a valve body on bottom of CP4, and can be read out from camera image found here:  https://lhocds.ligo-wa.caltech.edu/cr_screens/png/video0-1.png. The other three TCs are:  TC#2 reads air near GV 11 (east end); TC#3 reads air at exit of heater duct (west end); TC#4 reads air at top near GN2 regen pipe. 

We discovered a bigger problem - the air in east end of enclosure is not being circulated because the supply and return are on top of each other at west end, so the east side (GV11) is heating at a higher rate. Tomorrow we will work with contractors to install an extension duct at return to balance air mix. We decided to stop the heater for tonight to protect GV11. (edit:  the heater had already tripped because at least one of the four TCs had exceeded the setpoint+10C - good to know the safety protocol works!)